Tungsten electrodes have high melting point, corrosion resistance, high density, good thermal and electrical conductivity.

Due to the properties of tungsten, it is well suited for TIG welding and other electrode materials for this type of work. Adding rare earth oxides to tungsten metal to stimulate its electron work function improves the welding performance of tungsten electrodes: the arc starting performance of the electrode is better, the stability of the arc column is higher, and the electrode burnout rate is smaller. Common rare earth additives include cerium oxide, lanthanum oxide, zirconium oxide, yttrium oxide and thorium oxide.

In tungsten electrodes, more importantly, they also have different tungsten content, and the final color is also different. When welding, choose the right tungsten electrode to make welding easier and it is important to get a high-quality weld. Some important factors to consider in making the right choice are the type of power source (inverter or transformer), welding material (steel, aluminum or stainless steel) and material thickness.

Cerium Tungsten Electrode

Cerium oxide is added to tungsten to produce cerium tungsten electrodes. The specific data are as follows:

Type   Dopant    Doping Amount    Other Doping Amount    Electron Work Function   Color Coating Head

WC20 CeO2 1.80~2.20%<0.20% 2.7~2.8 Grey

Cerium tungsten has the following advantages over thorium tungsten material:

Non-radiative, low melting rate, long welding life, good arc starting. Therefore, cerium tungsten is the best substitute for thoriated tungsten in low current welding environment.

Cerium tungsten electrodes are mainly used in low current DC welding. Cerium tungsten has excellent arc starting performance at low current, so it has become the standard of most rail pipe welding equipment manufacturers, in addition, it is also used in other low current applications such as welding of fine parts.

Cerium tungsten is not suitable for applications under high current conditions, because under such conditions, the oxide will quickly move to the high heat area, that is, the top of the electrode weld, which will cause damage to the uniformity of the oxide. The above-mentioned benefits brought by the uniform distribution of the material will no longer exist.

Lanthanum Tungsten Electrode

Lanthanum oxide is added to tungsten to produce tungsten-lanthanum electrodes. The specific data are as follows:

Type   Dopant    Doping Amount    Other Doping Amount    Electron Work Function   Color Coating Head

WL10 La₂O₃ 0.80~1.20%<0.20% 2.6~2.7 Black

WL15 La₂O₃ 1.30~1.70%<0.20% 2.8~3.0 Golden

WL20 La₂O₃ 1.80~2.20%<0.20% 2.8~3.2 Sky Blue

Better mechanical cutting performance, better creep resistance, high recrystallization temperature and good ductility.

Lanthanum-tungsten electrode is already the most popular electrode material in the world, especially the lanthanum-tungsten electrode with a content of 1.5% (different from 2.0%)

Scientific research shows that 1.5% lanthanum tungsten has the conductivity closest to that of 2.0% tungsten thorium. Therefore, welders can easily change the electrode without changing the parameters of the equipment.

In 1998, there was a famous field test, which was to weld 2.0% tungsten thorium electrode, 2.0% tungsten cerium electrode and 1.5% lanthanum tungsten electrode provided by the two manufacturers at 70 A and 150 a current and 300 V DC respectively. As a result, in these two cases, 1.5% lanthanum tungsten electrode showed its excellent welding performance, and also reflected its characteristics of low burn rate.

Lanthanum tungsten electrode is also suitable for AC welding tasks, and its performance is excellent.

Thorium Tungsten Electrode

Thorium oxide is doped in tungsten to produce thorium tungsten electrode. Specific data are as follows:

Type   Dopant    Doping Amount    Other Doping Amount    Electron Work Function   Color Coating Head

 WT10 ThO₂ 0.90~1.20% Yellow

WT20 ThO₂ 1.8~2.2% Red

WT30 ThO₂ 2.80~3.20% Purple

WT40 ThO₂ 3.80~4.20% Orange

Compared with pure tungsten materials, thorium tungsten has the following characteristics:

*Lower Electronic Function * Higher Crystallization Temperature * Better Conductivity

 * Good Mechanical Cutting Performance.

Thorium tungsten electrode is a widely used tungsten electrode material, which has superior welding performance than pure tungsten, so it is widely used in the field of DC welding.

Thorium tungsten electrode is easy to operate and can work well even under overload current.

Nevertheless, people are gradually turning their attention to other types of tungsten electrodes, such as tungsten cerium and tungsten lanthanum, not only because they show excellent performance in most applications, but also, importantly, they do not emit radiation harm. Because the thorium oxide in thorium tungsten electrodes produces a small amount of radiation, some welders are reluctant to approach them.

When welding with thorium tungsten electrodes, it is necessary to maintain a good ventilation environment, and the discarded welding joints should be properly disposed of.

Zirconium Tungsten Electrode

Zirconium oxide is doped into tungsten to produce zirconium-tungsten electrodes. The specific data are as follows:

Type   Dopant    Doping Amount    Other Doping Amount    Electron Work Function   Color Coating Head

WZ3 ZrO₂ 0.20~0.40%<0.20% 2.5~3.0 Brown

WZ8 ZrO₂ 0.70~0.90%<0.20% 2.5~3.0 White

Like pure tungsten electrodes, zirconium tungsten electrodes can only be welded in an alternating current environment.

The zirconium tungsten electrode has good welding performance in the alternating current environment. Especially in the case of high load current, the superior performance of zirconium-tungsten electrodes is irreplaceable by other electrodes.

During welding, the end of the zirconium-tungsten electrode can be kept in a spherical shape to reduce the phenomenon of tungsten infiltration, and has good corrosion resistance.

Due to the emergence of other alternative products, the demand for zirconium-tungsten electrodes will tend to decrease. The main alternative is tungsten lanthanum electrodes.

Yttrium Tungsten Electrode

When yttrium tungsten electrode is welded, the arc beam is slender and the degree of compression is large, and its penetration depth is relatively large at medium and large currents. It is mainly used in the military industry and aerospace industry. Zirconium oxide is doped into tungsten to produce zirconium-tungsten electrodes. The specific data are as follows:

Type   Dopant    Doping Amount    Other Doping Amount    Electron Work Function   Color Coating Head

WY YO₂ 1.80~2.20%<0.20% 2.0~3.9 Blue